The secondary aim of this project is to collect information regarding the subjective drug effects of each of the four interventions. This information, in conjunction with data showing how each treatment affects brain activity, permits the visualization of the neurobiological substrates of drug action. For instance, in a previous study we found that zolpidem-induced increases in self-reported ratings of "like", "high", and intoxication were related to increased brain activity in specific limbic networks. Our data were consistent with those areas shown previously to undergo hemodynamic or metabolic alterations in association with the subjective states of intoxication following administration of cocaine, alcohol, and hydromorphone, and they speak to a body of literature implicating limbic, paralimbic, and mesocortical regions in mediating the actions of psychotropic drugs. Because alprazolam is known to possess more abuse potential in general, results from the present study may confirm our previous findings while also demonstrating that investigating pharmacological effects on brain activity may help identify the neural correlates of drug action and behavior, thereby revealing the functional significance of GABAergic modulation on intrinsic brain activity.